package com.looso.sfolder.security;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Random;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

public class DES {

	private static final String KEY = "ABCDEFGH";
	private Key key;

	/**
	 * 根据参数生成KEY
	 */
	public void getKey(String strKey) {
		try {
			KeyGenerator _generator = KeyGenerator.getInstance("DES");
			_generator.init(new SecureRandom(strKey.getBytes()));
			this.key = _generator.generateKey();
			_generator = null;
		} catch (Exception e) {
			throw new RuntimeException(
					"Error initializing SqlMap class. Cause: " + e);
		}
	}

	/**
	 * 文件file进行加密并保存目标文件destFile中
	 * 
	 * @param file
	 *            要加密的文件 如c:/test/srcFile.txt
	 * @param destFile
	 *            加密后存放的文件名 如c:/加密后文件.txt
	 */
	public void encrypt(String file, String destFile) throws Exception {
		Cipher cipher = Cipher.getInstance("DES");
		// cipher.init(Cipher.ENCRYPT_MODE, getKey());
		cipher.init(Cipher.ENCRYPT_MODE, this.key);
		InputStream is = new FileInputStream(file);
		OutputStream out = new FileOutputStream(destFile);
		CipherInputStream cis = new CipherInputStream(is, cipher);
		byte[] buffer = new byte[1024];
		int r;
		while ((r = cis.read(buffer)) > 0) {
			out.write(buffer, 0, r);
		}
		cis.close();
		is.close();
		out.close();
	}

	/**
	 * 文件采用DES算法解密文件
	 * 
	 * @param file
	 *            已加密的文件 如c:/加密后文件.txt * @param destFile 解密后存放的文件名 如c:/
	 *            test/解密后文件.txt
	 */
	public void decrypt(String file, String dest) throws Exception {
		Cipher cipher = Cipher.getInstance("DES");
		cipher.init(Cipher.DECRYPT_MODE, this.key);
		InputStream is = new FileInputStream(file);
		OutputStream out = new FileOutputStream(dest);
		CipherOutputStream cos = new CipherOutputStream(out, cipher);
		byte[] buffer = new byte[1024];
		int r;
		while ((r = is.read(buffer)) >= 0) {
			cos.write(buffer, 0, r);
		}
		cos.close();
		out.close();
		is.close();
	}

	public CipherInputStream decrypt(InputStream is) throws Exception {
		Cipher cipher = Cipher.getInstance("DES");
		cipher.init(Cipher.DECRYPT_MODE, this.key);

		CipherInputStream cis = new CipherInputStream(is, cipher);

		return cis;
	}

	private static final String ALGORITHM_DES = "DES";
	public static byte[] decryptByDES(byte[] source, byte[] key)
			throws NoSuchAlgorithmException, NoSuchPaddingException,
			InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
		SecretKey deskey = new SecretKeySpec(key, ALGORITHM_DES);

		Cipher c1 = Cipher.getInstance(ALGORITHM_DES);
		c1.init(Cipher.DECRYPT_MODE, deskey);
		byte[] clearByte = c1.doFinal(source);

		return clearByte;
	}
	public static byte[] decryptByDES(byte[] source){
		try {
			return decryptByDES(source, KEY.getBytes());
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return null;
		} 
	}
	
	public static byte[] decryptByDES(String key, byte[] source) {
		try {
			return decryptByDES(source, key.getBytes());
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return null;
		}
	}

	public static String randomKeyString(int length) {
		Random randGen = null;
		char[] numbersAndLetters = null;
		if (length < 1) {
			return null;
		}
		if (randGen == null) {
			randGen = new Random();
			numbersAndLetters = ("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
					.toCharArray();
		}
		char[] randBuffer = new char[length];
		for (int i = 0; i < randBuffer.length; i++) {
			randBuffer[i] = numbersAndLetters[randGen.nextInt(numbersAndLetters.length)];
		}
		return new String(randBuffer);
	}
}
